Some detectors, such as X-ray detectors or optical detectors in sensors for fingerprint recognition, may require a relatively high detection sensitivity. Examples of such sensors include optical detectors integrated in thin-film-transistor liquid-crystal-display (TFT-LCD) display screens, and further, optical detectors integrated in high pixels-per-inch (PPI) TFT-LCD display screens. A high detection sensitivity in an optical detector requires a large-area photosensitive region, i.e., a high aperture opening ratio of the corresponding array.